Late life onset schizophrenic illness shows important similarities and differences compared to cases with onset in early adult life. We propose to examine cerebral structural, bloodflow and dopamine D2 receptor changes associated with late life onset schizophrenia using MRI, SPECT and PET scanning. C-11 labelled N-methyl spiroperidol used as the PET ligand will yield Bmax values of dopamine D2 receptors. Bmax values will be compared to those previously reported to accompany normal aging and those found in early onset schizophrenia. Matched comparison and control groups will consist of elderly normal volunteers and currently elderly, early onset schizophrenics. We also propose to examine other conditions leading to hallucinatory/delusional syndromes in the elderly, to address issues of specificity and mechanism. Brain structural, bloodflow and receptor measures will be analyzed to determine their (covariance) association with carefully characterized clinical symptomatology, neuropsychologic abnormalities, sensory deficits and social factors. This may aid understanding of late life onset schizophrenia, and clarify the relationship of this syndrome both to the early onset illness and to the psychopathology of aging and of psychosis.